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    <title>Document</title>
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    <!-- 有一个数组存了 1 万个字符串，如何把一万个字符串分成 N 组，当输入第 N 组时，打印该组的所有元素 -->
    <script>
      let arr = ['12', '23', '34', '45', '56', '67', '78', '89', '90', '09', '98', '87', '76', '65', '54', '43', '32', '21']
      let result = []
      for (var i = 0; i < arr.length; i += 3) {
        result.push(arr.slice(i, i + 3))
      }
      console.log(result[1])
    </script>
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